East Portal, Black Canyon of Gunnison

East Portal, Black Canyon of Gunnison

Big enough to be overwhelming, still intimate enough to feel the pulse of time, Black Canyon of the Gunnison exposes you to some of the steepest cliffs, oldest rock, and craggiest spires in North America. Over the course of two million years, the Gunnison River paired with relentless weathering to carve through pristine Precambrian metamorphic rock—slicing open dark, crystalline gneiss and schist that date back nearly 1.8 billion years. This dramatic gorge carved its way into regional heritage at East Portal, where early 20th-century engineers constructed the ambitious Gunnison Tunnel. Completed in 1909 and designated a National Historic Civil Engineering Landmark, the 5.8-mile diversion tunnel was an extraordinary feat that redirected river water through solid rock to irrigate the surrounding Uncompahgre Valley, forever tying human ingenuity to the vertical wilderness of rock, water, and sky.

Virtually unknown even to Colorado riders, but available to you on BigRingVR, East Portal Road presents one of the most brutal vertical challenges in the region. Dropping sharply from the South Rim down to the riverbed, the ascent back out demands absolute focus. Use those 2k of flat warm-up wisely, because the next 5k averaging 12%—with relentless pitches spiking up to 16% through hairpin switchbacks—are going to hurt really bad. Climbing out from the deep shadow of the canyon floor back to the rim requires relentless pacing as you fight double-digit gradients carved straight into the ancient cliffside.